All are "equally" important depending on the author. For an author with weak contents, a full power upvote only will make him/her sit up and want to earn more. From there he/she could be on the trending page, gather more followers and resteems and work smart to live up to the new found fame.

A resteem could place the author in a position of opportunity for authors who dedicate time to good content.

A follow only helps good and fabulous authors who generate amazing content